1993 Gen V rebuilds

[Rusted Nut]

Pulled and disassembled both engines. 1526 hours. Had the boat for two seasons. Port engine a little on the weak side. Port burned 12% more fuel during a 841 gal summer vacation trip- best trip ever. Both had blow by.
Sbd engine original bearing and timing chain. Main and rod bearing -great. Chain was shot, valves had wear. Walls look great , no taper.
Port engine had main bearing dated 99. Had a single roller TC. Valves were worn. 6 out of 8 pistons had the compression ring gaps stacked- lined up. Cylinder walls measure out- no taper.
Doing new valve springs. Cams spec out.
33gph @ 21kts 3200. Props were tuned in 2016.
My question - has anyone run a different cam for this size of boat?
Looking for low end torque.

 

[Espos4]

Be careful with cam swaps. As you know, marine engines have raw water mixed with the exhaust. Too much valve overlap is a very bad thing.

Even if you are just looking for more bottom end torque, make sure you compare all of the cam specs to the original.

 

[hottoddie]

4 years ago I had both my 454s rebuilt at a very reputable engine shop South of Boston. The owner wrote the specs for new cams and had them confirmed by the engineers at Comp Cams. The specs were very mild and designed to avoid exhaust reversion and get a small increase in HP. When done the engines were run on dynos and resulted in 380hp. Not a big increase but resulted in an increase of 1-2mph at 3000rpm cruise. So far after 3 seasons and 150hrs all is well. Engines run great, no leaks and virtually no oil consumption.

 

[Rusted Nut]

4 years ago I had both my 454s rebuilt at a very reputable engine shop South of Boston. The owner wrote the specs for new cams and had them confirmed by the engineers at Comp Cams. The specs were very mild and designed to avoid exhaust reversion and get a small increase in HP. When done the engines were run on dynos and resulted in 380hp. Not a big increase but resulted in an increase of 1-2mph at 3000rpm cruise. So far after 3 seasons and 150hrs all is well. Engines run great, no leaks and virtually no oil consumption.

I have read your build at marineengine.com( I think). What kind of torque did she make?

 

[hottoddie]

I'd have to dig out the dyno sheets to find the torque specs and they are in the boat at the yacht club. If I have a chance I'll grab them and post.

 

[Rusted Nut]

I'd have to dig out the dyno sheets to find the torque specs and they are in the boat at the yacht club. If I have a chance I'll grab them and post.

I would be interested in seeing that. I have never seen a torque rating from mercruiser. Do you track your fuel burn?

 

[Rusted Nut]

4 years ago I had both my 454s rebuilt at a very reputable engine shop South of Boston. The owner wrote the specs for new cams and had them confirmed by the engineers at Comp Cams. The specs were very mild and designed to avoid exhaust reversion and get a small increase in HP. When done the engines were run on dynos and resulted in 380hp. Not a big increase but resulted in an increase of 1-2mph at 3000rpm cruise. So far after 3 seasons and 150hrs all is well. Engines run great, no leaks and virtually no oil consumption.

Can share to the cam specs you used?

 

[hottoddie]

Ok I just dug out the engine dyno and rebuild specs. The engine torque ranged from 419ft.lbs.@2500rpms, 447ft.lbs.@3000rpms, 452ft.lbs@3300rpms, 457ft.lbs.@3600rpms,444ft.lbs.@3900rpms, 431ft.lbs.@4200rpms. Interesting that max. hp. is 374@5000rpms. and 255@3000rpms. So when you here people say hp. is not important that is why.

Camshaft is a Comp Cams CB5006/5129-H-115.0. The specs are 223/227@0.50 >516/.523LS115.0
Cam specs on a stock 454/330hp are 213/217duration .460/.480 lift 114LSA.
Cam specs on a 454/502 Magnum are 224/224duration .510/.510 lift 115.5LSA
The camshaft blank for the opposite rotation engine was a little hard to source in 2015 when they were built so today it may be more difficult. The specs were kept in a reasonable range for an engine that has wet exhaust to avoid exhaust reversion. So far I am happy with how they run and if anyone has anymore questions I will try to answer them.

 

[joeyleggz]

Very interesting specs with that competition cam ,here’s my Dyno sheets from my stock rebuild on a gen six 454 The dyno was not able to pick up the lower poles But it was suspected that a 27 ,2800 RPM the torque was somewhere around 480-490ish My engines came with the peanut port heads make tremendous low-end torque I happen to run my boat around 32 to 3300 RPM both engines matched almost perfectly on the specs

 

[Rusted Nut]

Ok I just dug out the engine dyno and rebuild specs. The engine torque ranged from 419ft.lbs.@2500rpms, 447ft.lbs.@3000rpms, 452ft.lbs@3300rpms, 457ft.lbs.@3600rpms,444ft.lbs.@3900rpms, 431ft.lbs.@4200rpms. Interesting that max. hp. is 374@5000rpms. and 255@3000rpms. So when you here people say hp. is not important that is why.

Camshaft is a Comp Cams CB5006/5129-H-115.0. The specs are 223/227@0.50 >516/.523LS115.0
Cam specs on a stock 454/330hp are 213/217duration .460/.480 lift 114LSA.
Cam specs on a 454/502 Magnum are 224/224duration .510/.510 lift 115.5LSA
The camshaft blank for the opposite rotation engine was a little hard to source in 2015 when they were built so today it may be more difficult. The specs were kept in a reasonable range for an engine that has wet exhaust to avoid exhaust reversion. So far I am happy with how they run and if anyone has anymore questions I will try to answer them.

Thank you for looking it up.
Nice numbers..
Did you set the cam at 0 or advance it?
Did you change prop specs also?

 

[Rusted Nut]

View attachment 65741 Very interesting specs with that competition cam ,here’s my Dyno sheets from my stock rebuild on a gen six 454 The dyno was not able to pick up the lower poles But it was suspected that a 27 ,2800 RPM the torque was somewhere around 480-490ish My engines came with the peanut port heads make tremendous low-end torque I happen to run my boat around 32 to 3300 RPM both engines matched almost perfectly on the specs

Strong build!
Peanut heads, unshrouded valves, minor bowl work, new valve springs.
Will look into this CompCam tomorrow.
Trying to source roller rockers that fit under the stock genV valve covers.

 

[hottoddie]

Rusted nut I can't answer your question re: the cam position. I can tell you the build included Eldelbrock Performer intake manifolds, Comp Cam Stamped rocker arms, Comp Cams springs and Melling oil pumps. The blocks were bored .030 over with new flat top pistons and molly rings. I did change props from the stock Sea Ray 19X18 three blades to 20X17 three blades. The boat tops out at 31mph @4100rpms when launched in the spring with clean bottom, running gear and cool air. Late summer it tops out at 29mph so that's pretty decent. Fuel flow on Garmin flow meters is about 30gph @ 20/21mph which is typical for a 390 gasser when running properly. I thought about changing to roller rockers but as you know they won't fit under the stock covers and changing the covers will cause interference with the exhaust manifolds so I opted for the Comp Cam stamped rockers.

 

[Rusted Nut]

Rusted nut I can't answer your question re: the cam position. I can tell you the build included Eldelbrock Performer intake manifolds, Comp Cam Stamped rocker arms, Comp Cams springs and Melling oil pumps. The blocks were bored .030 over with new flat top pistons and molly rings. I did change props from the stock Sea Ray 19X18 three blades to 20X17 three blades. The boat tops out at 31mph @4100rpms when launched in the spring with clean bottom, running gear and cool air. Late summer it tops out at 29mph so that's pretty decent. Fuel flow on Garmin flow meters is about 30gph @ 20/21mph which is typical for a 390 gasser when running properly. I thought about changing to roller rockers but as you know they won't fit under the stock covers and changing the covers will cause interference with the exhaust manifolds so I opted for the Comp Cam stamped rockers.

I would 30gph burn is great for that 390. I can’t justify to myself( ok my wife) to go that far in upgrades. Keep original cams and might play with cam timing.

 

[Rusted Nut]

Dropping off oil coolers to get checked/rebuilt.

Thank you for all replies.

 

[hottoddie]

I also replaced the U coolers on my Crusaders as well as all the hoses and belts. Didn't want to have any issues for a long time. I had replaced the alternators with one wire Delco style alternators a couple of years prior to the engines being redone also.

 

[Rusted Nut]

Short blocks are done.

 

[ttmott]

Interesting - didn't the BBC mercruisers have forged cranks?

 

[Rusted Nut]

The magnums has forged cranks. These are not.

 

[hottoddie]

The magnums has forged cranks. These are not.

This is what I've was told by the owner of the shop the did my rebuilds 4 years ago. He also stated that the cast crank blocks are fine up to 500hp and 4500rpm.

 

[Espos4]

Interesting - didn't the BBC mercruisers have forged cranks?

Definitely looks like a cast iron crank.
These appear to be the casting lines. The one on the right looks like it was ground down a little, probably from balancing the rotating assembly.